A process which involves fusion called "a cera persa" which means involving the loss of the wax has been known according to which the models are made in wax or similar plastic material. Then the models are covered with gypsum and the models are introduced into a furnace kept at high temperature, so that the initial model disappears and! in the gypsum remains the cavity within which subsequently the metal which can be silver, gold or platinum or an alloy of these materials is injected. The finished article is obtained by solidification.
The form in the gypsum is subsequently crushed and the process is called "a cera persa".